Development of tabular broadband antenna for UHF-TV

A tabular loop antenna is proposed that can be matched to the characteristic impedance of a coaxial cable without using complex parasitic elements or expensive matching elements while maintaining the broadband character and superior gain of the loop antenna. Specifically, modification of the aperture shape inside the loop is attempted without changing the external shape. In this way, the control of the input impedance becomes possible and the bandwidth for VSWR less than or equal to 2 can reach about 40% at the center frequency of 620 MHz for UHF-band TV An antenna with a unidirectional radiation pattern with a reflector was fabricated for trial and was studied both by experiments and by FDTD analysis. It was confirmed that the bandwidth for VSWR less than or equal to 2 reaches about 50% at 620 MHz. Further, with regard to the dynamic gain, a stable gain of 7.6 to 8.2 dBi was attained for the entire UHF band. This antenna will be useful for ground wave digital broadcasting. (C) 2003 Wiley Periodicals, Inc.